Machine for producing surfaces of optical lenses, for example toric surfaces

ABSTRACT

Machine for forming predetermined surfaces, such as toric surfaces on optical lenses. The machine is of a type in which the surfaces are determined by a base cam and by a transverse cam which is caused to move lengthwise of the base cam. The machine further has a frame, a first holder for a rotatable cup-shaped cutting tool, a second holder for the workpiece and coordinating mechanism for producing predetermined relative movement between said holders. The apparatus is particularly characterized in that the coordinating mechanism so controls the holders that the workpiece axis on the tool axis are always in the same plane or parallel planes and the relative movement between the holders comprises movement along axes which are positioned perpendicularly to one another. A device is provided for effecting automatic operation and for obtaining a wide range of adjustability to permit the manufacture of lenses having a wide range of contours, said latter including convex, concave and variable contours.

United States Patent 1191 Brueck Aug. 26, 1975 MACHINE FOR PRODUCINGSURFACES OF OPTICAL LENSES, FOR EXAMPLE TORIC SURFACES Appl. No.:402,320

FOREIGN PATENTS OR APPLICATIONS 977,720 4/1951 France 1. 51/124 LPrimary Examiner--Othell M. Simpson Attorney, Agent, or FirmWoodhams,Blanchard and Flynn [5 7 ABSTRACT Machine for forming predeterminedsurfaces, such as toric surfaces on optical lenses. The machine is of atype in which the surfaces are determined by a base cam and by atransverse cam which is caused to move lengthwise of the base cam. Themachine further has a [30] Foreign Application Priority Data Oct 26 972German 2252498 frame, a first holder for a rotatable cup-shaped cuttingy tool, a second holder for the workpiece and coordinat- [52] U S C]5l/100 51/55 51/124 L ing mechanism for producing predetermined relative[51] Int Cl B24b 17/10- i324 9/14 movement between said holders. Theapparatus is par- [58] Fie'ld 'g 51/55 54 93 100 R ticularlycharacterized in that the coordinating mecha- 51/157 nism so controlsthe holders that the workpiece axis n the tool axis are always in thesame plane or para]- [56] References Cited lel planes and the relativemovement between the STA S P NTS holders comprises movement along axeswhich are po- UNITED TE ATE sitioncd perpendicularly to one another. Adevice is 2,47 .021 194 DAvaucourt 1/1 R provided for effectingautomatic operation and for ob- 2,633,675 4/1953 Ellis 51/124 L m g awide range of adjustability to p i the g g manufacture of lenses havinga wide range of con- 8/1969 352 5l/284 tours, said latter includingconvex, concave and vari- 3,492, 764 2/1970 Dalton 51/124 L able3,670,460 6/1972 Oldfield Ct al. 51/124 L 11 Claims 8 Drawing Figures$704,554 12/1972 Laughman 51/55 l 43 34 9 1 537 25 '1 39 11 32A 27 I as42 -so zs 35 32 31 QM 53 PATENTED A'UGZS I975 SQU 3 BF 6PATENTEBAUGZSIBYS sum 5 or 6 MACHINE FOR PRODUCING SURFACES OF OPTICALLENSES, FOR EXAMPLE TORIC SURFACES FIELD OF THE INVENTION The inventionrelates to a machine for producing surfaces for optical lenses,particularly toric lens surfaces, wherein such surfaces are defined by abase cam and by a transverse cam which is moved along said base cam. Itrefers further to apparatus including a frame, a first holder for arotatable cup-shaped cutting tool with a cutting lip which linearlycontacts the workpiece, wherein the diameter of the tool and the slopedposition of its axis relative to the base cam determines the form of thetransverse cam particularly with respect to a nonrotatable workpiece. Italso includes a second holder for the workpiece, particularly therotatable cutting tool, and a coordinating mechanism for producing apredetermined relative movement between the first and second holder.

BACKGROUND OF THE INVENTION In discussing the invention, the manufactureof toric lens surfaces should be considered to facilitate anunderstanding thereof, such manufacture of toric lens surfaces havinggreat importance in the manufacture of eyeglasses. The invention is,however, not limited to machines with which toric lens surfaces can bemanufactured inasmuch as the cams which are identified hereinafter asbase cam and cylinder cam can also depart from a circular, or anapproximately circular, shape.

A toric surface is created by the rotation of a circular are at acertain distance around an axis which lies in the same plane as thecircular arc. If the distance from the axis of rotation is larger thanthe circular arc radius, then a ring torus is created; if the distanceis smaller, then a ton torus is created. In general toric surfaces ofeyeglesses are parts of ring tori. The circle along which the producingcircular arc of the torus is moved will be identified hereinafter as thebase cam and the producing circular arc itself will be identified as thecylinder cam.

In manufacturing toric lens surfaces, cup-shaped tools are usually used,as illustrated schematically in FIGS. 1 and 2 of the drawings. Theannular cutting lip b is brought into contact with the workpiece and isswung at a selected radius R about the workpiece. The radius which isthus produced on the workpiece is the above-mentioned base cam. Forproducing a cylinder cam having a selected curvature, the axis ofrotation c of the cup-shaped tool a is adjusted in the plane of the basecam at a certain angle Bto the line which connects the pivotalcenterpoint and the cutting lip point p which produces the base cam.During the production of the base cam the cylinder cam is producedsimultaneously. The adjusting angle ,3 for determining the cylinder camdepends on the diameter of the tool. In known machines positive (convex)and negative (concave) base cams are produced by changing the distancebetween the pivotal centerpoint 0 and the cutting lip b. In order toachieve an as large as possible positive and negative radius zone, theknown machines must be provided with correspondingly long carriageguides which, to obtain the necessary rigidity for the machine, requiressame to be made very heavy. The long carriage guides and the greatmasses resulting therefrom require a horizontal arrangement of the planeof movement of the carriage. In general the limits for the radius of thebase cam lie at i 200 mm.

By using a cup-shaped tool, the cylinder cam, as stated above, isdetermined by the sloped position of the tool. The cylinder cam,therefore, frequently departs slightly from an exactly circular arc.However, the deviation is so small that it as a rule can be accepted.

The basic purpose of the invention is to construct a machine of the typementioned above in such a manner that the radius of the base cam may beof any desired size, including infinite, with only a small size ofmachine.

This purpose is attained according to the invention by providing suchcoordinating mechanism, which consists of a control mechanismcontrolling one or both holders, that the workpiece axis and the toolaxis remain always in the same plane or in parallel planes and therelative movement between the holders comprises a pivotal movement and amovement along axes which are positioned perpendicularly to one another.

In the machine of the invention the base cam is not directly passedthrough by the tool or workpiece. The same relative positions betweentool and workpiece, as they exist in the known machines, are hereachieved in such a manner that a selected sloped position of the toolaxis relative to the workpiece axis is fixedly coordinated with aselected relative position of tool and workpiece in a retangularcoordinate system. In the inventive machine the movement which iscarried out in known machines by a pivoted arm is divided into movementsalong rectangular coordinates and a slopedposition movement. In thismanner, a very compact design is obtained because only paths of movementof the size of the workpiece diameter are needed and a change of thebase cam does not require any adjusting between tool and workpieceholder. The movements can easily be so controlled that during stockremoval the same relative movements between workpiece and tool arecreated, as would be created in the case of an as much as possible shortor a very long, in a border case an infinitely long, swinging arm, as itwould be necessary in known machines. The movements can also becoordinated in such a manner that the base cam is neither a straightline (infinite radius) nor a circle (finite radius) but instead has anypath, including a path which is variable and of interest in themanufacture of special eyeglasses, for example eyeglasses with areas ofdifferent refractive power.

In a preferred embodiment of the invention, the first holder is movablerelative to the machine frame along coordinates which are positionedrectangularly to one another and the second holder is pivotable about anaxis which is arranged fixedly on the machine frame. This division ofthe movements results in a structurally very simple machine and one inwhich the moving mechanisms for achieving the pivotal movement of thesecond holder can be arranged fixedly on the machine frame. This ispossible because the pivotal axis is stationary relative to the machineframe.

BRIEF DESCRIPTION OF THE DRAWINGS There are many possible embodimentsfor this machine. ,One exemplary embodiment of the invention isillustrated in the drawings, in which:

FIG. 1 illustrates three different relative positions between theconcave side of an optical lens and a cupshaped tool,

FIG. 2 is a corresponding illustration, wherein relative positions of acup-shaped tool to a convex lens surface are illustrated,

FIG. 3 is a top view of a machine according to the invention,

FIG. 4 is a vertical cross-sectional view along the line IV--IV of FIG.3,

FIG. 5 is a cross-sectional view along the line V-V of FIG. 3,

FIG. 6 illustrates a part of the machine,

FIG. 7 is a schematic illustration for explaining the operation of themachine during the manufacture of a concave lens surface and FIG. 8 isan illustration corresponding to FIG. 7 for the manufacture of a convexlens surface.

DETAILED DESCRIPTION The machine has a frame 60 (FIG. 3) on which arearranged a first holder which is collectively identified by thereference numeral 61 (FIG. 4) and a second holder which is collectivelyidentified by the reference numeral 62. On the inside 63 of thehousing-like frame there are arranged the control means for coordinatingthe movements of the first holder 61 and the second holder 62. In theillustrated exemplary embodiment, the first holder 61 is the workpieceholder and the second holder 62 is the tool holder.

The tool 1 is so arranged with respect to its annular cutting lip 2 thatthe centerpoint of the cutting lip radius coincides with the swivel axis3 for the second holder 62. The tool 1 is secured on a tool spindle 4which is clamped in a spindle head 5. The spindle head 5 is providedwith a carriage guide 6 and can be laterally adjusted by means of athreaded spindle 7. This adjustability serves to adjust the machine tovarious diameters of the tool 1.

The spindle head 5 is connected to a pivotally mounted arm 8 through acarriage guide 6, said arm being secured on a shaft which is supportedrotatably in the machine frame 60 (also called machine column). The axisof the shaft 9 corresponds to the mentioned pivotal or swivel axis 3.The tool spindle 4 is driven by a motor 11 (FIG. 5) The pivotal movementof the tool 1 is produced by means of a hydraulic piston 13 which hasteeth 14 mating with a gear 12 secured on the shaft 9.

The workpiece 15 is adhesively fastened to a workpiece holder 16 whichis secured on a liftable and lowerable rod 17 identified hereinafter asa quill. The quill 17 is provided with an annular piston 18 and issupported axially movably in a machine table 19 comprising a carriage.The quill 17 is secured against rotation by a guide rod 20. The axialmovement is caused by hydraulic pressure fluid applied onto the annularpiston 18.

The machine table 19 is guided movably alongside guideways 21perpendicularly to the quill axis on the machine column 60. The machinetable is moved by means of a hydraulic cylinder 23. In the illustratedexemplary embodiment, the transverse movement of the axis 22 of thequill and the swinging movement of the axis 64 of the tool spindle 4both occur in a single plane. A conventional hydraulic power unit 24supplies the hydraulic pressure. The hydraulic lines are notillustrated.

A control cam 25 for producing the base cam is mounted on a holder 26which is provided on the machine table 19. A scanning arm 27 which isguided in guide bearings scans the control cam 25. A guide arm 29 isprovided on the scanning arm 27, which guide arm is aligned exactlyparallel to the guideways 21 of the machine table 19. A feeler 31 ismounted on an arm 30 which is secured on the quill 17, which feeler hasa scanning pin 32 which abuts under spring pressure the guide arm 29.The feeler 31 transmits during movement of the scanning pin 32 apositive or negative control voltage corresponding with the direction ofmovement. This voltage is amplified in an amplifier, not illustrated,and is fed to a hydraulic servovalve 33. Same controls the flow ofhydraulic liquid to the cylinder 34 in which the annular piston 18 ismovable so that the quill 17 is moved in the same direction as thescanning pin 32 and thereby returns the feeler 31 into its zeroposition.

A further control cam 35 for the swinging movement of the tool 1 ismounted on a holder 36 which is identical with the holder 26 for thecontrol cam 25 provided on the machine table 19. A rocking lever 37which is rotatably supported on a shaft 38 scans the control cam 35. Anadjsuting piece 39 for adjusting the angle B (see FIGS. 1 and 2) forselecting the cylinder cam is mounted on the rocking lever 37. Thescanning pin 41 of a feeler is pressed by spring pressure against theadjusting piece 39.

The feeler 40 is secured on an arm 42 which in turn is fixedly connectedto the shaft 38. The shaft 38 is rotatably supported in bearings 43. Adisk 44 is positioned fixed with respect to rotation of the shaft 38, onwhich disk a steel band is secured which loops around the disk 44 at adesired angle. The steel band 45 is secured with its other end on anequally large disk 46 and loops around same also at a selected angle.The disk 46 is connected fixedly with respect to rotation on and withrespect to the shaft 9 to provide a mechanical connection through thesteel band 45 between control cam 35 and tool 1 in such a manner thatthe sloped position of the tool, namely its swivel position with respectto the axis 3, is in a fixed relation to the position of the feeler 40and therewith of the fixed control cam.

The steel band is held under tension by means of a weight 47. The weight47 hangs on a rope 48 which is placed over a disk 44 which in turn isconnected fixedly with respect to rotation of the shaft 38. The weightcan also be replaced by a spring.

The feeler 40 is connected in the same manner as the feeler 31 to aservovalve 50 through a power amplifier. The servovalve 50 controls theflow of a hydraulic liquid to the hydraulic piston 13.

OPERATION The machine operates as follows:

For selecting a certain base cam the associated control cam 25 isinserted into the holder 26. Also for the control of the swinging orrocking movement a (see FIGS. 1 and 2) a selected control cam 35 ismounted onto the holder 36. One particular control cam 25 is alwaysassociated with a given control cam 35. It is thereby advantageous (toavoid mix-ups) to combined both cams into one unit and so to select thearrangement of the feelers that the control cams can be exchanged as oneunit. In the schematic illustration two separate control cams areillustrated for clarity.

To create a certain cylinder cam a corresponding adjusting piece 39 isinserted into the mounting of the rocking lever 37 and the adjustingangle ,8 (FIGS. 1 and 2) is thereby adjusted.

For working of the lens surface (illustrated is the treatment of aconvex lens surface), the workpiece is brought into contact with therotating tool 1 and the machine table 19 together with the workpiece 15is moved by the hydraulic cylinder 23 into the swinging plane of thetool axis. The surface can be worked in one passage, namely during onemovement of the machine table 19 from left to right (seen in FIG. 4),and the lens surface is completed.

During the movement of the machine table, the control cams 25 and whichare fixedly connected to the machine table 19, are moved relative to thescanning mechanisms. The scanning arm 27 and the rocking lever 37 arethus moved and move the scanning pins 32 and 41 of the feelers 31 and40. Control signals in the form of positive or negative control voltagesare thereby created. These signals are amplified through the poweramplifiers and are fed to the servovalves 33 and 50.

The servovalve 33 controls the flow of hydraulic liquid into thehydraulic cylinder 34 and thus the movement of the quill 17 on which theworkpiece 15 is provided. At the same time, the feeler 31 is moved inthe same direction as the scanning pin 32. This enables the workpiece tocarry out a movement which equals the contour of the control cam.

The servovalve 50 controls the flow of hydraulic liquid to the cylinder65 in which the piston 13 is movable. Said piston acts through the teeth14 to move the swinging arm 8 on which the tool 1 is mounted. Throughthe disks 44 and 46 and the steel band 45, the shaft 38 with the arm 42and the feeler is swung at the same angle as the scanning pin 41. Thepivotal movement of the rocking lever 37 which is effected by thecontrol cam 35 is thus transmitted onto the workpiece 1. By a suitableamplification of the signals in the power amplifiers the controldeviation is kept sufiiciently small that the manufacture tolerances arenot exceeded. Very exacting control is possible because the movement ofthe feelers which cooperate with the control cams 25, 35 is relativelyslow.

It is evident from an inspection of the drawings that by selectingsuitable control cams 25 and 35 any desired connection between themovement of the workpiece and the swinging movement of the tool can becreated. A control cam 25 with a straight line as a controlling contourcorresponds with an infinite radius for the base cam. If then thecylinder cam is to have a constant value over the entire lens surface,the control cam 35 would also have a straight line as a controllingcontour because the sloped position of the tool would remain unchangedduring the passage of the workpiece. The base cam may have any desiredform. The cylinder cam can also be changed during the grinding of a lenssurface.

The operating principle of the aforedescribed machine will be discussedagain hereinafter in connection with FIG. 8.

The cup-shaped cutting tool a is moved during its operation so that itsaxis 0 carries out a swinging movement; the pivotal angle through whichsaid tool acts during one passage is identified with a. The workpiecedoes not carry out a rotation; however, it does provide lifting andlowering movements and a movement in horizontal direction is superposedonto these movements. At the start of a working cycle, the workpiece andtool have the relative positions with respect to one another which areillustrated with thin full lines. Later the workpiece is lowered andmoves at the same time to the left. The tool is thereupon raised. Afterhalf of the passage is completed, the parts occupy the relativepositions illustrated in thick full lines. During the further operation,the workpiece moves again upwardly, whereby the tool at the same time isagain raised until finally at the end of the working the parts occupythe positions illustrated in dashed lines.

The manufacture of a concave surface occurs in an analogous manner whichcan be easily understood from FIG. 7 and therefore does not need to beexplained further.

Theinvention has been discussed above in connection with one example inwhich control cams were used for the correlation of workpiece movementand tool movement. However, different embodiments will also fall withinthe scope of the invention. For example a digital control apparatus (seebroken line illustration in FIG. 3) could be used which transmitscoordinated impulses to a movement mechanism for the swinging movementof the one'holder and the movement along coordinates the other holder.In place of hydraulic movement mechanisms, electrical movementmechanisms or combined mechanisms can also be used.

Although a particular preferred embodiment of the invention has beendisclosed above for illustrative purposes, it will be understood thatvariations or modifications thereof which lie within the scope of theappended claims are fully contemplated.

I claim: 1. A grinding and polishing machine, comprising: a frame; guidemeans mounted on said frame; first holder means comprising carriagemeans mounted on said guide means and adapted to move along a first pathrelative to said frame and quill means mounted on said carriage meansfor movement along a second path and in a direction perpendicular to thedirection of said first path of movement of said carriage means, saidfirst and second paths of movement defining a theoretical plane; secondholder means mounted on said frame for pivotal movement above a fixedpivot axis thereon;

cup-shaped tool means mounted on one of said quill means and said secondholder means, said cupshaped tool having a rim thereon;

workpiece holding means mounted on the other of said quill means andsaid second holder and adapted to hold a workpiece so that it willengage said rim of said cup-shaped tool means in response to a movementof said carriage means along said first path; and

control means for controlling the movement of said quill means and saidsecond holder means and, consequently, said workpiece holding means andsaid cup-shaped tool in response to said movement of said carriage meansalong said first path.

2. A grinding and polishing machine according to claim 1, wherein saidcup-shaped tool is mounted on said second holder means and saidworkpiece holding means is mounted on said quill means.

3. A grinding and polishing machine according to claim 1, wherein saidcontrol means includes control cams and feelers adapted to engage saidcontrol cams.

4. A grinding and polishing machine according to claim 3, wherein saidcontrol means for controlling the pivoting movement of said secondholder means includes an exchangeable adjusting piece which correspondsto a certain relative position between workpiece and tool.

5. A grinding and polishing machine according to claim 3, wherein saidcontrol means includes control cams for controlling said first andsecond holders, said control cams being connected to one of saidcarriage means and said frame.

6. A grinding and polishing machine according to claim 5, wherein saidcontrol means includes feeler means which cooperate with said controlcams, said feeler means including signal generating means fortransmitting signals to amplifiers which in turn act onto adjustingmembers for simultaneously adjusting the relative position between saidtool means and said workpiece holding means.

7. A grinding and polishing machine according to claim 1, wherein saidquill means includes a longitudinally movable rod which is guided insaid carriage means and which is movable perpendicularly to thedirection of movement of said carriage means.

8. A grinding and polishing machine according to claim 7, wherein saidcontrol means includes control cams; and

wherein said control cams are mounted on said carriage means.

9. A grinding and polishing machine according to claim 7, wherein saidrod has a piston thereon which is movable in an operating cylinder onsaid carriage means and is adapted to receive pressure medium on bothsides thereof to control the movement thereof.

10. A grinding and polishing machine according to claim 7, wherein saidsecond holder means is fixedly connected to a pivotal shaft which issupported on said frame; and

wherein said control means comprises a pair of relatively movablecontrol cams and feelers, said feelers contacting said control cams andadapted to produce a signal in response to a movement of said feelersrelative to said control cam, one of said feelers being coupled forcontrolling the swinging movement through a mechanical gearing to apivotal shaft so that a rotary position of said pivotal shaftcorresponds to a position of said one feeler.

11. A grinding and polishing machine according to claim 10, wherein saidone feeler is fixedly connected to a feeler shaft and being rotatabletherewith, a windup disk mounted on said feeler shaft and a band fixedlysecured to and extending between said pivotal shaft and said wind-updisk.

1. A grinding and polishing machine, comprising: a frame; guide means mounted on said frame; first holder means comprising carriage means mounted on said guide means and adapted to move along a first path relative to said frame and quill means mounted on said carriage means for movement along a second path and in a direction perpendicular to the direction of said first path of movement of said carriage means, said first and second paths of movement defining a theoretical plane; second holder means mounted on said frame for pivotal movement above a fixed pivot axis thereon; cup-shaped tool means mounted on one of said quill means and said second holder means, said cup-shaped tool having a rim thereon; workpiece holding means mounted on the other of said quill means and said second holder and adapted to hold a workpiece so that it will engage said rim of said cup-shaped tool means in response to a movement of said carriage means along said first path; and control means for controlling the movement of said quill means and said second holder means and, consequently, said workpiece holding means and said cup-shaped tool in response to said movement of said carriage means along said first path.
 2. A grinding and polishing machine according to claim 1, wherein said cup-shaped tool is mounted on said second holder means and said workpiece holding means is mounted on said quill means.
 3. A grinding and polishing machine according to claim 1, wherein said control means includes control cams and feelers adapted to engage said control cams.
 4. A grinding and polishing machine according to claim 3, wherein said control means for controlling the pivoting movement of said second holder means includes an exchangeable adjusting piece which corresponds to a certain relative position between workpiece and tool.
 5. A grinding and polishing machine according to claim 3, wherein said control means includes control cams for controlling said first and second holders, said control cams being connected to one of said carriage means and said frame.
 6. A grinding and polishing machine according to claim 5, wherein said control means includes feeler means which cooperate with said control cams, said feeler means including signal generating means for transmitting signals to amplifiers which in turn act onto adjusting members for simultaneously adjusting the relative position between said tool means and said workpiece holding means.
 7. A grinding and polishing machine according to claim 1, wherein said quill means includes a longitudinally movable rod which is guided in said carriage means and which is movable perpendicularly to the direction of movement of said carriage means.
 8. A grinding and polishing machine according to claim 7, wherein said control means includes control cams; and wherein said control cams are mounted on said carriage means.
 9. A grinding and polishing machine according to claim 7, wherein said rod has a piston thereon which is movable in an operating cylinder on said carriage means and is adapted to receive pressure medium on both sides thereof to control the movement thereof.
 10. A grinding and polishing machine according to claim 7, wherein said second holder means is fixedly connected to a pivotal shaft which is supported on said frame; and wherein said control means comprises a pair of relatively movable control cams and feelers, said feelers contacting said control cams and adapted to produce a signal in response to a movement of said feelers relative to said control cam, one of said feelers being coupled for controlling the swinging movement through a mechanical gearing to a pivotal shaft so that a rotary position of said pivotal shaft corresponds to a position of said one feeler.
 11. A grinding and polishing machine accorDing to claim 10, wherein said one feeler is fixedly connected to a feeler shaft and being rotatable therewith, a wind-up disk mounted on said feeler shaft and a band fixedly secured to and extending between said pivotal shaft and said wind-up disk. 